drain and overflow hole size and compatability of tub waste /drain

I just purchased the Kohler Seaforth cast iron 54" tub. My alcove is 58 and7/8". On the tub specs there is no size specified on the size of the outlets. I call Kohler and I'm told outlets are 2 and 1/4". I was planning on using the Moen rough out kit and the Moen drain kit (2 piece) drain and overflow cover. There are no size dimensions for the exterior dimensions of the tubes that goes into the tub. I call Moen and I'm told they are an 1 inch 7/8. None of this seems right to me. I thought they are "standard". I could just use the recommended Moen K-7213 unit at $109, but I don't want a mechanical drain. We almost exclusively shower so I want to save a few dollars and avoid mechanical issues. Doesn't it seem like the Moen rough out kit will work. Any other suggestions. Thanks

I'm measuring the finished walls. A small bathroom. One end wall is close to the toilet and the other wall could be ripped out and re framed but it's so much easier with the smaller tub. I also reasoned that the plumbing will not need to be adapted too much if at all. There is now a very used and tired fiberglass shower/tub enclosure. I will have some space from the end of tub to the wall and plan on some kind of bezel or tile in that space. I saw somewhere that you can buy marble, granite, and Corion wrap arounds to go around the top of the tub to the wall space. Anyone know about these? So, what do you think? Should I have enlarged the space for a 5" longer tub that's mainly used as a shower. Thanks for you answer about the waste.

A 54" bathtub ALWAYS costs more than a 60", sometimes by a little and often by a lot, so using the larger tub would be cost effective, especially since you would not have to do a lot of construction to make the smaller one work. These days the openings on bathtubs are "standardized" so any waste and overflow will work.

A 54" bathtub ALWAYS costs more than a 60", sometimes by a little and often by a lot, so using the larger tub would be cost effective, especially since you would not have to do a lot of construction to make the smaller one work. These days the openings on bathtubs are "standardized" so any waste and overflow will work.

I greatly appreciate the help and I called HD. No problem canceling my order 'til tomorrow so I didn't cancel yet...but then I thought about building a shelf or ledge at the end of the tub since I'll have 5"-6" to play with providing I stay with the shorter tub. I think this would look better and be more usable for shampoo and the like than a niche. I know it would need to be slightly sloped for drainage. Any thoughts? I feel really nuts right now as always when starting a project and not having done it before.

A tub is expected in a house, even it most of the time it is used for a shower. A 'standard' tub is often so uncomfortable, that it is only used for bathing children. Getting one even shorter means there would be no real comfortable way to bath if you really did want a soak unless you were height challenged. I opted for a 6' tub and would really have liked a 7' one! No way I'd go for a shorter one.

While you could build a shelf, to get it done well with no leaks and eventual rot, you'd have to tear out the walls and start over. So, if that was the case, I think you'd be better off with a standard 5' tub. Since you'll have most of the walls out already (well, the drywall), you can then straighten the walls, which are unlikely to be nice and flat, then rebuild it to today's standards. This could include numerous niches, if you desired. Make sure that the tub you order has a built-in tiling flange, and it will be much easier to make things water-tight. Many people think the tile is the waterproof layer. But, a properly built shower is water-tight without the tile installed...the tile is the window dressing and durability layer, not the waterproofing layer. To get that, you often need to start from the bare studs.

After the advice here, I'm going for a 60" tub (Maax I think) That tub comes with the rough out kit for the drain and overflow holes in the tub. My concern was getting the correct plumbing for those openings.